CHAPTER 11 This chapter describes how to configure EtherChannels and to apply and configure the Link Aggregation Control Protocol (LACP) for more efficient use of EtherChannels in Cisco NX-OS. This chapter includes the following sections: Information About EtherChannels, page 11-1, page 11-7 Verifying Port-Channel Configuration, page 11-12 Information About EtherChannels An EtherChannel bundles up to eight individual interfaces into a group to provide increased bandwidth and redundancy. Port channeling also load balances traffic across these physical interfaces. The EtherChannel stays operational as long as at least one physical interface within the EtherChannel is operational. You create an EtherChannel by bundling compatible interfaces. You can configure and run either static EtherChannels or EtherChannels running the Link Aggregation Control Protocol (LACP). (See Understanding LACP section on page 11-4 for information on LACP.) Any configuration changes that you apply to the EtherChannel are applied to each member interface of that EtherChannel. For example, if you configure Spanning Tree Protocol (STP) parameters on the EtherChannel, the Cisco NX-OS applies those parameters to each interface in the EtherChannel. You can use static EtherChannels, with no associated protocol, for a simplified configuration. For more efficient use of the EtherChannel, you can use the Link Aggregation Control Protocol (LACP), which is defined in IEEE 802.3ad. When you use LACP, the link passes protocol packets. This section includes the following topics: Understanding EtherChannels, page 11-2 Compatibility Requirements, page 11-2 Load Balancing Using EtherChannels, page 11-3 Understanding LACP, page 11-4 11-1
Information About EtherChannels Chapter 11 Understanding EtherChannels Using EtherChannels, Cisco NX-OS provides wider bandwidth, redundancy, and load balancing across the channels. You can collect up to eight ports into a static EtherChannel or you can enable the Link Aggregation Control Protocol (LACP). with LACP requires slightly different steps than configuring static EtherChannels (see the section on page 11-7). Cisco NX-OS does not support Port Aggregation Protocol (PAgP) for EtherChannels. An EtherChannel bundles individual links into a channel group to create a single logical link that provides the aggregate bandwidth of up to eight physical links. If a member port within an EtherChannel fails, traffic previously carried over the failed link switches to the remaining member ports within the EtherChannel. Each port can be in only one EtherChannel. All the ports in an EtherChannel must be compatible; they must use the same speed and operate in full-duplex mode (see the Compatibility Requirements section on page 11-2). When you are running static EtherChannels, without LACP, the individual links are all in the on channel mode; you cannot change this mode without enabling LACP (see the Port-Channel Modes section on page 11-6). You cannot change the mode from ON to Active or from ON to Passive. You can create an EtherChannel directly by creating the port-channel interface, or you can create a channel group that acts to aggregate individual ports into a bundle. When you associate an interface with a channel group, Cisco NX-OS creates a matching EtherChannel automatically if the EtherChannel does not already exist. You can also create the EtherChannel first. In this instance, Cisco NX-OS creates an empty channel group with the same channel number as the EtherChannel and takes the default configuration. The EtherChannel is operationally up when at least one of the member ports is up and that port s status is channeling. The EtherChannel is operationally down when all member ports are operationally down. Compatibility Requirements When you add an interface to a channel group, Cisco NX-OS checks certain interface attributes to ensure that the interface is compatible with the channel group. Cisco NX-OS also checks a number of operational attributes for an interface before allowing that interface to participate in the port-channel aggregation. The compatibility check includes the following operational attributes: Port mode Access VLAN Trunk native VLAN Allowed VLAN list Speed 11-2
Chapter 11 Information About EtherChannels 802.3x flow control setting MTU The Cisco Nexus 5000 Series switch only supports system level MTU. This attribute cannot be changed on an individual port basis. Broadcast/Unicast/Multicast Storm Control setting Priority-Flow-Control Untagged CoS Use the show port-channel compatibility-parameters command to see the full list of compatibility checks that Cisco NX-OS uses. You can only add interfaces configured with the channel mode set to on to static EtherChannels. You can also only add interfaces configured with the channel mode as active or passive to EtherChannels that are running LACP. (See the Port-Channel Modes section on page 11-6 for information on port-channel modes.) You can configure these attributes on an individual member port. When the interface joins an EtherChannel, the following individual parameters are replaced with the values on the EtherChannel: Bandwidth MAC address Spanning Tree Protocol The following interface parameters remain unaffected when the interface joins an EtherChannel: Description CDP LACP port priority Debounce Load Balancing Using EtherChannels Cisco NX-OS load balances traffic across all operational interfaces in an EtherChannel by reducing part of the binary pattern formed from the addresses in the frame to a numerical value that selects one of the links in the channel. EtherChannels provide load balancing by default and the basic configuration uses the following criteria to select the link: For a Layer 2 frame, it uses the source and destination MAC addresses. For a Layer 3 frame, it uses the source and destination MAC addresses and the source and destination IP addresses. For a Layer 4 frame, it uses the source and destination MAC addresses, the source and destination IP addresses, and the source and destination port number. You can configure the switch to use one of the following methods to load balance across the EtherChannel: Destination MAC address Source MAC address MAC address Destination IP address 11-3
Information About EtherChannels Chapter 11 Source IP address IP address Destination TCP/UDP port number Source TCP/UDP port number TCP/UDP port number Table 11-1 shows the criteria used for each configuration: Table 11-1 EtherChannel Load-Balancing Criteria Configuration Layer 2 Criteria Layer 3 Criteria Layer 4 Criteria Destination MAC Destination MAC Destination MAC Destination MAC Source MAC Source MAC Source MAC Source MAC MAC MAC MAC Destination IP Destination MAC Destination MAC, destination IP MAC Destination MAC, destination IP Source IP Source MAC Source MAC, source IP Source MAC, source IP IP Destination TCP/UDP port MAC Destination MAC MAC, source and destination IP Destination MAC, destination IP MAC, source and destination IP Destination MAC, destination IP, destination port Source TCP/UDP port Source MAC Source MAC, source IP Source MAC, source IP, source port TCP/UDP port MAC MAC, source and destination IP MAC, source and destination IP, source and destination port Use the option that provides the balance criteria with the greatest variety in your configuration. For example, if the traffic on an EtherChannel is going only to a single MAC address and you use the destination MAC address as the basis of port-channel load balancing, the EtherChannel always chooses the same link in that EtherChannel; using source addresses or IP addresses might result in better load balancing. Understanding LACP LACP allows you to configure up to 8 interfaces into an EtherChannel. This section includes the following topics: LACP Overview, page 11-5 LACP ID Parameters, page 11-5 Port-Channel Modes, page 11-6 LACP Marker Responders, page 11-7 11-4
Chapter 11 Information About EtherChannels LACP-Enabled and Static EtherChannels Differences, page 11-7 LACP Overview You must enable LACP before the feature functions. Figure 11-1 shows how individual links can be combined into LACP EtherChannels and channel groups as well as function as individual links. Figure 11-1 Individual Links Combined into an EtherChannel Channel group1 Switch A 1/1 1/2 1/3 1/4 po1 Port channel po2 Channel group 2 2/1 2/ 2 2/3 2/4 Switch B 1/5 Individual link 2/5 187537 With LACP, you can bundle up to eight interfaces in a channel group. When you delete the EtherChannel, Cisco NX-OS automatically deletes the associated channel group. All member interfaces revert to their previous configuration. You cannot disable LACP while any LACP configurations are present. LACP ID Parameters LACP uses the following parameters: LACP system priority Each system that runs LACP has an LACP system priority value. You can accept the default value of 32768 for this parameter, or you can configure a value between 1 and 65535. LACP uses the system priority with the MAC address to form the system ID and also uses the system priority during negotiation with other devices. A higher system priority value means a lower priority. The LACP system ID is the combination of the LACP system priority value and the MAC address. LACP port priority Each port configured to use LACP has an LACP port priority. You can accept the default value of 32768 for the LACP port priority, or you can configure a value between 1 and 65535. LACP uses the port priority with the port number to form the port identifier. LACP uses the port priority to decide which ports should be put in standby mode when there is a limitation that prevents all compatible ports from aggregating and which ports should be put into active mode. A 11-5
Information About EtherChannels Chapter 11 Port-Channel Modes higher port priority value means a lower priority for LACP. You can configure the port priority so that specified ports have a lower priority for LACP and are most likely to be chosen as active links, rather than hot-standby links. LACP administrative key LACP automatically configures an administrative key value equal to the channel-group number on each port configured to use LACP. The administrative key defines the ability of a port to aggregate with other ports. A port s ability to aggregate with other ports is determined by these factors: Port physical characteristics, such as the data rate, the duplex capability, and the point-to-point or shared medium state Configuration restrictions that you establish Individual interfaces in EtherChannels are configured with channel modes. When you run static EtherChannels, with no protocol, the channel mode is always set to on. After you enable LACP globally on the device, you enable LACP for each channel by setting the channel mode for each interface to active or passive. You can configure either channel mode for individual links in the LACP channel group. You must enable LACP globally before you can configure an interface in either the active or passive channel mode. Table 11-2 describes the channel modes. Table 11-2 Channel Mode passive active on Channel Modes for Individual Links in an EtherChannel Description LACP mode that places a port into a passive negotiating state, in which the port responds to LACP packets that it receives but does not initiate LACP negotiation. LACP mode that places a port into an active negotiating state, in which the port initiates negotiations with other ports by sending LACP packets. All static EtherChannels, that is, that are not running LACP, remain in this mode. If you attempt to change the channel mode to active or passive before enabling LACP, the device returns an error message. You enable LACP on each channel by configuring the interface in that channel for the channel mode as either active or passive. When an LACP attempts to negotiate with an interface in the on state, it does not receive any LACP packets and becomes an individual link with that interface; it does not join the LACP channel group. Both the passive and active modes allow LACP to negotiate between ports to determine if they can form an EtherChannel, based on criteria such as the port speed and the trunking state. The passive mode is useful when you do not know whether the remote system, or partner, supports LACP. Ports can form an LACP EtherChannel when they are in different LACP modes as long as the modes are compatible as in the following examples: A port in active mode can form an EtherChannel successfully with another port that is in active mode. A port in active mode can form an EtherChannel with another port in passive mode. 11-6
Chapter 11 LACP Marker Responders A port in passive mode cannot form an EtherChannel with another port that is also in passive mode because neither port will initiate negotiation. A port in on mode is not running LACP. Using EtherChannels, data traffic may be dynamically redistributed due to either a link failure or load balancing. LACP uses the Marker Protocol to ensure that frames are not duplicated or reordered because of this redistribution. Cisco NX-OS supports only Marker Responders. LACP-Enabled and Static EtherChannels Differences Table 11-3 provides a brief summary of major differences between EtherChannels with LACP enabled and static EtherChannels. Table 11-3 EtherChannels with LACP Enabled and Static EtherChannels Configurations EtherChannels with LACP Enabled Static EtherChannels Protocol applied Enable globally. Not applicable. Channel mode of links Can be either: Can only be On. Maximum number of links in channel Active Passive 8 8 You can configure multiple EtherChannels on a device. This section includes the following topics: Creating an EtherChannel, page 11-7 Adding a Port to an EtherChannel, page 11-8 Configuring Load Balancing Using EtherChannels, page 11-9 Enabling LACP, page 11-10 Configuring Port-Channel Port Modes, page 11-10 Configuring the LACP System Priority and System ID, page 11-11 Configuring the LACP Port Priority, page 11-11 Creating an EtherChannel You can create an EtherChannel before creating a channel group. Cisco NX-OS automatically creates the associated channel group. 11-7
Chapter 11 If you want LACP-based EtherChannels, you need to enable LACP (see the Enabling LACP section on page 11-10). To create an EtherChannel, perform this task: Step 1 Enters configuration mode. Step 2 switch(config)# interface port-channel channel-number Specifies the port-channel interface to configure, and enters the interface configuration mode. The range is from 1 to 4096. Cisco NX-OS automatically creates the channel group if it does not already exist. This example shows how to create an EtherChannel: switch (config)# interface port-channel 1 To remove the EtherChannel and delete the associated channel group, perform this task: switch(config)# no interface port-channel channel-number Removes the EtherChannel and deletes the associated channel group. See the Compatibility Requirements section on page 11-2 for details on how the interface configuration changes when you delete the EtherChannel. Adding a Port to an EtherChannel You can add a port to a new channel group or to a channel group that already contains ports. Cisco NX-OS creates the EtherChannel associated with this channel group if the EtherChannel does not already exist. If you want LACP-based EtherChannels, you need to enable LACP (see the Enabling LACP section on page 11-10). To configure an EtherChannel, perform this task: Step 1 Enters configuration mode. Step 2 Step 3 switch(config)# interface type slot/port switch(config-if)# switchport mode trunk Specifies the interface that you want to add to a channel group and enters the interface configuration mode. (Optional) Configures the interface as a trunk port. 11-8
Chapter 11 Step 4 Step 5 switch(config-if)# switchport trunk {allowed vlan vlan-id native vlan vlan-id} switch(config-if)# channel-group channel-number 1. This is called implicit EtherChannel creation. (Optional) Configures necessary parameters for a trunk port. Configures the port in a channel group and sets the mode. The channel-number range is from 1 to 4096. Cisco NX-OS creates the EtherChannel associated with this channel group if the EtherChannel does not already exist 1. To remove the port from the channel group, perform this task: switch(config)# no channel-group Removes the port from the channel group. The port reverts to its original configuration. This example shows how to add an Ethernet interface 1/4 to channel group 1: switch (config)# interface ethernet 1/4 switch(config-if)# switchport mode trunk switch(config-if)# channel-group 1 Configuring Load Balancing Using EtherChannels You can configure the load-balancing algorithm for EtherChannels that applies to the entire device. If you want LACP-based EtherChannels, you need to enable LACP (see the Enabling LACP section on page 11-10). To configure load balancing using EtherChannels, perform this task: Step 1 Enters configuration mode. Step 2 Step 3 switch(config)# port-channel load-balance ethernet {destination-ip destination-mac destination-port source-dest-ip source-dest-mac source-dest-port source-ip source-mac source-port} switch(config-router)# show port-channel load-balance Specifies the load-balancing algorithm for the device. The range depends on the device. The default is source-dest-mac. (Optional) Displays the port-channel load-balancing algorithm. This example shows how to configure source IP load balancing for EtherChannels: 11-9
Chapter 11 switch (config)# port-channel load-balance ethernet source-ip To restore the default load-balancing algorithm of source-dest-mac for non-ip traffic and source-dest-ip for IP traffic, perform this task: switch(config)# no port-channel load-balance ethernet Restores the default load-balancing algorithm. Before Release 4.0(1a)N1 of Cisco NX-OS, the source-dest-ip, source-dest-mac, and source-dest-port keywords were source-destination-ip, source-destination-mac, and source-destination-port, respectively. Enabling LACP LACP is disabled by default; you must enable LACP before you begin LACP configuration. You cannot disable LACP while any LACP configuration is present. LACP learns the capabilities of LAN port groups dynamically and informs the other LAN ports. Once LACP identifies correctly matched Ethernet links, it facilitates grouping the links into an EtherChannel. The EtherChannel is then added to the spanning tree as a single bridge port. To enable LACP, perform this task: Step 1 Enters configuration mode. Step 2 switch(config)# feature lacp Enables LACP on the switch. Step 3 switch(config)# show system internal clis feature (Optional) Displays enabled features. This example shows how to enable LACP: switch (config)# feature lacp Configuring Port-Channel Port Modes After you enable LACP, you can configure the channel mode for each individual link in the LACP EtherChannel as active or passive. This channel configuration mode allows the link to operate with LACP. When you configure EtherChannels with no associated protocol, all interfaces on both sides of the link remain in the on channel mode. 11-10
Chapter 11 To configure the LACP link mode, perform this task: Step 1 Enters configuration mode. Step 2 Step 3 switch(config)# interface type slot/port switch(config-if)# channel-group number mode {active on passive} switch(config-if)# no channel-group number mode Specifies the interface to configure, and enters the interface configuration mode. Specifies the port mode for the link in an EtherChannel. After LACP is enabled, you configure each link or the entire channel as active or passive. When you run EtherChannels with no associated protocol, the port-channel mode is always on. The default port-channel mode is on. Returns the port mode to on for the specified interface. This example shows how to set the LACP-enabled interface to active port-channel mode for Ethernet interface 1/4 in channel group 5: switch (config)# interface ethernet 1/4 switch(config-if)# channel-group 5 mode active Configuring the LACP System Priority and System ID The LACP system ID is the combination of the LACP system priority value and the MAC address. To configure the LACP system priority, perform this task: Step 1 Enters configuration mode. Step 2 Step 3 switch(config)# lacp system-priority priority switch(config-if)# show lacp system-identifier Configures the system priority for use with LACP. Valid values are 1 through 65535, and higher numbers have lower priority. The default value is 32768. Displays the LACP system identifier. This example shows how to set the LACP system priority to 2500: switch(config)# lacp system-priority 2500 Configuring the LACP Port Priority When you enable LACP, you can configure each link in the LACP EtherChannel for the port priority. 11-11
Verifying Port-Channel Configuration Chapter 11 To configure the LACP link mode and port priority, perform this task: Step 1 Enters configuration mode. Step 2 Step 3 switch(config)# interface type slot/port switch(config-if)# lacp port-priority priority Specifies the interface to configure, and enters the interface configuration mode. Configures the port priority for use with LACP. Valid values are 1 through 65535, and higher numbers have lower priority. The default value is 32768. This example shows how to set the LACP port priority for Ethernet interface 1/4 to 40000: switch (config)# interface ethernet 1/4 switch(config-if)# lacp port priority 40000 Verifying Port-Channel Configuration To display port-channel configuration information, perform one of the following tasks: switch# show interface port-channel channel-number switch# show system internal clis feature switch# show lacp {counters interface type slot/port neighbor port-channel system-identifier} switch# show port-channel compatibility-parameters switch# show port-channel database [interface port-channel channel-number] switch# show port-channel load-balance switch# show port-channel summary switch# show port-channel traffic switch# show port-channel usage switch# show port-channel database Displays the status of a port-channel interface. Displays enabled features. Displays LACP information. Displays the parameters that must be the same among the member ports in order to join an EtherChannel. Displays the aggregation state for one or more port-channel interfaces. Displays the type of load balancing in use for EtherChannels. Displays a summary for the port-channel interfaces. Displays the traffic statistics for EtherChannels. Displays the range of used and unused channel numbers. Displays information on current running of the EtherChannel feature. 11-12